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Overview
Comment:Use the SQLITE_CONSTRAINT return value from xBestIndex to prohibit bad query plans in the pragma virtual table.
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SHA3-256: b1259d4448f744861e416f42328c1450854370e5c77102d2a5abe5cf6c7f12bd
User & Date: drh 2024-03-25 11:34:42
Context
2024-03-25
12:28
Fix recent test case changes so that they also work on Windows. (check-in: 38578b5a user: drh tags: trunk)
11:34
Use the SQLITE_CONSTRAINT return value from xBestIndex to prohibit bad query plans in the pragma virtual table. (check-in: b1259d44 user: drh tags: trunk)
10:55
Improvements to the vtablog.c extension: Eliminate memory leaks. More diagnostic output for xBestIndex. (check-in: 92e9a71b user: drh tags: trunk)
Changes
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Changes to src/pragma.c.

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  pIdxInfo->estimatedCost = (double)1;
  if( pTab->nHidden==0 ){ return SQLITE_OK; }
  pConstraint = pIdxInfo->aConstraint;
  seen[0] = 0;
  seen[1] = 0;
  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
    if( pConstraint->usable==0 ) continue;
    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    if( pConstraint->iColumn < pTab->iHidden ) continue;
    j = pConstraint->iColumn - pTab->iHidden;
    assert( j < 2 );
    seen[j] = i+1;
  }
  if( seen[0]==0 ){
    pIdxInfo->estimatedCost = (double)2147483647;
    pIdxInfo->estimatedRows = 2147483647;
    return SQLITE_OK;
  }
  j = seen[0]-1;
  pIdxInfo->aConstraintUsage[j].argvIndex = 1;
  pIdxInfo->aConstraintUsage[j].omit = 1;
  if( seen[1]==0 ){
    pIdxInfo->estimatedCost = (double)1000;
    pIdxInfo->estimatedRows = 1000;
    return SQLITE_OK;
  }
  pIdxInfo->estimatedCost = (double)20;
  pIdxInfo->estimatedRows = 20;

  j = seen[1]-1;
  pIdxInfo->aConstraintUsage[j].argvIndex = 2;
  pIdxInfo->aConstraintUsage[j].omit = 1;

  return SQLITE_OK;
}

/* Create a new cursor for the pragma virtual table */
static int pragmaVtabOpen(sqlite3_vtab *pVtab, sqlite3_vtab_cursor **ppCursor){
  PragmaVtabCursor *pCsr;
  pCsr = (PragmaVtabCursor*)sqlite3_malloc(sizeof(*pCsr));








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  pIdxInfo->estimatedCost = (double)1;
  if( pTab->nHidden==0 ){ return SQLITE_OK; }
  pConstraint = pIdxInfo->aConstraint;
  seen[0] = 0;
  seen[1] = 0;
  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
    if( pConstraint->iColumn < pTab->iHidden ) continue;
    if( pConstraint->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    if( pConstraint->usable==0 ) return SQLITE_CONSTRAINT;
    j = pConstraint->iColumn - pTab->iHidden;
    assert( j < 2 );
    seen[j] = i+1;
  }
  if( seen[0]==0 ){
    pIdxInfo->estimatedCost = (double)2147483647;
    pIdxInfo->estimatedRows = 2147483647;
    return SQLITE_OK;
  }
  j = seen[0]-1;
  pIdxInfo->aConstraintUsage[j].argvIndex = 1;
  pIdxInfo->aConstraintUsage[j].omit = 1;





  pIdxInfo->estimatedCost = (double)20;
  pIdxInfo->estimatedRows = 20;
  if( seen[1] ){
    j = seen[1]-1;
    pIdxInfo->aConstraintUsage[j].argvIndex = 2;
    pIdxInfo->aConstraintUsage[j].omit = 1;
  }
  return SQLITE_OK;
}

/* Create a new cursor for the pragma virtual table */
static int pragmaVtabOpen(sqlite3_vtab *pVtab, sqlite3_vtab_cursor **ppCursor){
  PragmaVtabCursor *pCsr;
  pCsr = (PragmaVtabCursor*)sqlite3_malloc(sizeof(*pCsr));
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